John mcconnell



J. McCONNELL.

PROCESS OF MANUFACTURING ELECTRIC STEEL. APPLICATION FILED MAR. 3'1.1919.

15318164. Patented 0ct. 7,1919.

steel.

Joan MccoNnELL, or CHICAGO, ILLINOIS.

PROCESS OF MANUFACTURING ELECTRIC STE-EL.

Specification of Letters Patent.

' Patented Oct. 7, 1919.

Continuation of applicationserial No. 210,803, filed January 8, 1918.This application filed March 31, 1919.

Serial No.

To all whom it may concern:

Be it known that I, JOHN MoCoNN LL, a citizen of the United States, anda residentof Chicago, county of Cook, and State of Illinois, haveinvented new and useful Improvements in Processes of ManufacturingElectric Steel, of which the following is a specification, the principleof the invention bein herein explained and the best mode in whici I havecontemplated applying that principle, so as to distinguish it from otherinventions.

This application is a continuation of my application for U. S. LettersPatent upon processes of manufacturing electric steel, Serial No.210,803, filed Jan. 8, 1918.-

My invention relates to processes of manufacturing electric steel.Particularly does it relate to the duplex processes of manufacturingopen-hearth electric-treatment steel and Bessemer-converterelectric-treatment That is 'to say, my process is an improvement in andto the open-hearth and Bessemer processes for the purpose, economicallyand in large tonnages,'of superrefining the molten products that saidopen-hearth and Bessemer processes yield and for making special steelstherefrom.

The objects of my invention are threefold: to obtain a large tonnage ata minimum cost, to obtain a more uniform product than any of which I amat present aware, and to require the use of less additions thanheretofore by saving losses therein.

My invention comprehends the use of a suitably large receptacle,preferably the usual acid-lined ladle, for receiving the product of anopen-hearth furnace, Bessemer-converter or other primary furnace, andrefining such product by means of an electric current in saidreceptacle, the alloys having been added gradually to said product whilebeing poured or tapped from the primary furnace to the receptacle, thecurrent then being applied to the mixture in the receptacle for acomparatively short period; for instance, approximately fifteen minutes,when treating a high-grade open-hearth product.

I am aware that processes have been disfifty (50) tons or more, forinstance,imay

be secured. at one operation the use .of

present standard equipment, and in order that heat may not be wasted intransferring the product to, and emptying the same into, a standardelectric furnace or other refining receptacle, which is usually locateda comparatively long distance from the primary furnace,-I prefer tosubject the mixture (if steel and additions to electric treatment in theladle or other receptacle which receives the product from the primaryfurnace, but th s is not necessary for obtaining the very {umformproduct, with the use of less addiparticularly'am I aware tions, which Isecure by adding the alloys to the product as the latter is dischargedfrom the primary furnace. Furthermore, a

fixed permanent position for electrification, including necessaryelectrodes, means for operating the latter, etc.,- may be establishedadj acently the primary furnace and the ladle may be transferred theretofor the electric treatment. This mechanical arrangement, however, ismerely suggestive and no claim to invention relative thereto is made inthis application.

The annexed drawing and the following description set forth in detailcertain means and steps illustrating and embodying my invention, thedisclosed means and steps,

however, constituting but one of the various forms in which theprinciple of the invention may be applied and by which it may be carriedout.

In said annexed drawing:

Figure 1 represents an arrangement of apparatus which serves as anillustration of means by which my improved process can be carried outwith reference to an open-hearth product, there being disclosed indotted lines the progress of the electrodes as the same are raisedgradually during the tapping of the furnace, such dotted linesillustrating the practice when the electric treatment is commenced asthe steel and additions enter the ladle, which is one of the forms ofthe improved process comprehended by the spirit of my invention;

Fig- 2 is illustrative of the conditions when dealing with anopen-hearth product, immediately following the finishing of the tappingand immediately prior to the lowering of the electrodes with the cover;and

Fig. 3 represents an arrangement of apparatus which serves as anillustration of means by which my improved process can be carried out inconnection with the operation of a Bessemer-converter.

With particular reference to Figs. 1 and 2, an acid-lined ladle of theusual construction is represented by 1, mounted upon a truck 2 which isadapted to be brought up to the open-hearth furnace .4 upon suitablerails in order to receive the product of said furnace, electrodes 3suitably supported, and raised and lowered manually or by automaticmeans well-known in this art, being provided for putting the productscontained in the ladle into the electric circuit. These electrodes 3extend and play through a ladle cover 5, Fig. 1, which is applied assoon as the charge has been tapped from the openhearth 4 into the ladle1, or which, Fig. 2,

is secured to the electrodes 3, if desired, and is raised and loweredwith the electrodes.

.With particular reference to Fig. 3, the conditions are shown inconnection with the carrying out of a duplex Bessemer-converter electrictreatment process, the difference between Figs. 1 and 3 being that thedotted line position of the electrodes, indicating the introduction ofthe same as soon as the charge is commenced to be poured, is omitted inFig. 3. ,This last-named condition, suggested by the dotted lines, Fig.1, is merely one of the methods of carrying out my invention and it isnot intended by illustrating the same in Fig. 1 that this method is theinvariable or even the preferred one.

While the furnace product is beingtapped or poured into the ladle 1,Iadd the desired alloys, in acold state, if desired, gradually to thesteel stream from a container 6, such alloys being in pure form, or inthe form of-ferro alloys, etc., as is referable and desirable, and alsoprefera 'ly crushed. The alloys which I mean and hereinafter claim asdesired alloys are those in which the losses are greatly reduced byreason of adding the same when and as added by my process and definitepercentages of which are desired in the final product and areprincipally chromium, manganese, tungsten, aluminum, silicon, vanadium,molybdenum, and combination of them, or combinations of one or more ofthese alloys with other additions. Of course, other alloys or acombination of them may be added for purposes other than to securedefinite percentages thereof in the final product, such as, for quietingthe steel by their affinity for oxygen or other impurities, thuscleansing the bath and making the product more homogeneous, and forperforming other desired functions. Illustrative of such other alloys istitanium. Also, illustrative of some alloys of which definitepercentages are desired in the final product and of which losses wouldnot be reduced by my process,

because they are not subject to losses in the primary furnace, isnickel. Particularly in the case of chromium has it been found that whenthe addition is introduced into the primary furnace, usually at the timeor just before tapping, there is a great variation in the product, thealloy being subject to fur nacereactions, causing it, among otherresults, to be oxidized and to go into the slag, so that large lossesoccur, sometimes in excess of thirty (30) per cent. of the amount ofchromium introduced into the primary furnace. My improved processgreatly reduces these losses, the atmosphere of the electric furnacebeing a neutral or a reducing one. In addition, my process insures avery uniform product. By my improved process also, even such aninfusible alloy as chromium can be satisfactorily assimilated in a coldstate, and it is not necessary to preheat the same and reduce it to amolten or semi-fluid condition. Thus, by my process,without previouscost and labor, except for grinding and powdering, a very infusiblealloy, such as chromium, is added, while at atmospheric temperature, tosteel of substantially three thousand degrees (3000) Fahrenheit highertemperature than the alloy and still a good distribution and combinationis secured.

When the open-hearth furnace is tapped, all of the product is allowed torun therefrom, including the slag, and 1 preferably allow a little ofthe slag 7 to remain in the ladle 1 for the purpose of keeping theproduct hot, Fig. 2, the balance of the slag being allowed to run offover the ladle, or being otherwise removed therefrom, as is commonpractice; of course, in the case of the Bessemerconverter, Fig. 3, therewill be only a slight amount of slag anyhow. I then apply the current tothe mixture of steel and alloys which gives a motion to the bath,completes the obtaining of a proper mix, removes the minute cavities ofslag that have arisen from internal chemical reactions, and effects thedesired refining, such application of the current being for acomparatively short period, for instance, fifteen minutes, when treatinga high-grade open-hearth product. Some of the incidental results of thiselectric treatment are the removal from the metal of some oxygen, theoxids going intothe slag, and the further purification from sulfur.

Particularly is my process applicable to the production of. chrome steelby the duplex open-hearth electric furnace method, overcoming thesomewhat prevalent opinion that only either steel refined entirely byelectric treatment or steel refined entirely by crucible treatment canbe practicably manufactured and still meet the requirements of desirablechrome steel and prov-i ing that, an open-hearth treatment combined withan electric refinement, in a proc-, ess carried out in the mannerhereinbefore detailed, will practicably produce a product meeting therequirements of desirable chrome steel.

It is well known that in the basic process of steel making a substantialamount of the phosphorus can always be removed. However, sulfur is moredifficult and uncertain to control. Sometimes .apparently equivalentconditions will remove greatly varying percentages of sulfur. If Idesire to re- .move additional sulfur in the ladle, by means other thantemperature, which is al-.

ways a potent factor in eliminating sulfur,

, I remove from the ladle quickly the small amount of slag 7 heretoforementioned, if it has been. allowed to remain in the ladle, and add'lim'eor a similar product, in,com-

. bination with fiuorspar, calcium chlorid or similar products whichwill increase the fusibility, if necessary, without lowering thebasicity, tomake a satisfactorily basic slag,

which will not only remove some of the sulfur, butwill absorb theimpurities and help in the refining by absorbing the oxidsfrom ahlesteel, as would have been done also by t e small amount of furnace slag.Sometimes also, the cost of pure stocks, the detriment to the primaryfurnace roof, the damage caused by dust carried over to the ports andcheckers, and the necessarily higher working temperatures, when removingsulfur 1n the primary furnace, make it advisable to remove much of thesulfur in the electric furnace rather than inthe primary furnace. Theelectric treatment is then applied. v

When my improved process comprehends the use of acid open-hearth steel,or Bessemer-converter steel, as manufactured in the-United States, it ispresupposed that the phosphorus content of the original materials whichare put into the open-hearth or converter is such as to insure thedesired phosphorus content of the final product, in-

converters have been used, particularly in Europe, in which phosphorusand some sulfur have been removed by employing a slag formed from meltedlime rock.

By the use of the process described above, 1

I obtain the results hereinbefore set out, of economically handlinglarge tonnages and securing a satisfactorily clean and homogeneousproduct in which the additions are most uniformly'distributed and forwhich,

because of the comparatively small losses, less additions are requiredthan in any procr ess heretofore known to me. Furthermore, the relativeloss of heat through the walls is also less for an electric furnacegiving large tonnages than for one giving comparatively small tonnages.

As plainly shown in Fig. 1, I do not limit myself to an application ofthe'electric treatment only after the product has been tapped or pouredinto the ladle, inasmuch as the conditions are often such in electricfurnace treatment that the current may be safely and practicably appliedas soon as the product has commenced to be poured into the electricfurnace, as is well known to those skilled 'in this art. This method ofapplyplying the electric treatment is illustrated in dotted lines, Fig.1, in which the dotted line position of the electrodes indicates how thelatter are gradually raised as the ladle 1 is gradually filled with thecharge and in which the position of the cover 5 shows how l the same isheld above the ladle 1, until the whole charge is tapped into the ladle,the electrodes meanwhile being gradually drawn up through the cover 5,and then the latter lowered upon the ladle when .the whole charge hasbeen tapped.

What I claim is:

1. In processes of manufacturing electric steel wherein the product ofan open-hearth furnace, Bessemer-converter, etc., is refined, the stepswhich consist, in pouring such product from the furnace into a suitablereceptacle; adding the desired alloys to .the product while beingpoured; and then subjecting the mixtureof steel and additions toelectric treatment.

, 2. In processes of man'ufacturing electric chrome steel wherein theproduct of an open-hearth furnace is refined, the steps which consist,in tapping such product from the furnace into a suitable receptacle;adding ferro-chro-me to the product'while being. tapped and thensubjecting the mixture 3 of steel and chromium to'elect-ric treatment.

3. In processes of manufacturing electric chrome steel wherein theproduct of an openhearth furnace is refined, the steps which consist, intapping such product from the furnace into the ladle, allowing some ofthe slag to remain in the ladle to keep the metal hot; addingferro-chrome to the product while being tapped; and then subjecting themixture of steel and chromium to electric treatment for substantiallyfifteen minutes.

4. In processes of manufacturing electric steel wherein the product ofan open-hearth furnace is refined, the steps which consist, in tappingsuch product from the furnace into a suitable receptacle; adding thedesired alloys to the product while being tapped; adding lime orasimilar product to form a "satisfactorily basic slag; and thensubjecting the mixture of steel and additions to electric treatment.

5. In processes of manufacturing electric steel wherein the product ofan open-hearth furnace, Bessemer-converter, etc., is refined,

the steps which consist, in pouring such product from the furnace into asuitable receptacle; allowing some slag to remain in the receptacle tokeep the metal hot; adding the desired alloys to the product while be1ngpoured; removing the slag; adding lime or a similar product to form asatisfactorily basic slag; and then subjecting the mixture of steel andadditions to electric treatment.

6. In processes of manufacturing electric chrome steel wherein theproduct of an openhearth furnace is refined, thesteps which consist, intapping such product from the furnace into the ladle; addingferro-chrome to the product while entering the ladle; adding lime or asimilar product to form a satisfactorily basic slag; and then subjectingthe mixture of steel and chromium to electric treatment.

7 In processes of manufacturing electric chrome steel wherein theproduct of an openhearth furnace is refined, the steps which consist, intapping such product from the furnace into the ladle, allowing a smallamount of the slag to remain in the ladle to I keep the metal hot;adding ferro-chrome to the product while entering the ladle; removingthe slag; adding lime or a similar product to form a satisfactorilybasic slag; and then subjecting the mixture of steel and chromium toelectric treatment.

8. In processes of manufacturing electric steel wherein the product ofan open-hearth furnace, Bessemer-converter, etc., is refined, the stepswhich consist, in pouring such product from the furnace into a suitablereceptacle; adding desired cold alloys to the product while beingpoured; and then subjecting the mixture of steel and additions toelectric treatment.

9. In processes of manufacturing electric chrome steel wherein theproduct of an openhearth furnace is refined, the stepswhich consist, intapping such product Ii'oin the furnace into a suitable receptacle;adding cold crushed ferro-chrome to the product while being tapped; andthen subjecting the mixture of steel and chromium to electric treatment.

10. In processes of manufacturing electric steel wherein the product ofan open-hearth furnace, Bessemer-converter, etc., i refined, the stepswhich consist, in pouring such product from the furnace into a suitablereceptacle; adding the desired alloys to the product while being poured;establishing an electriccurrent through the steel and additions as thesame enter the receptacle; and continuing such electric treatment for atime after the whole charge has been poured into the receptacle.

' 11. In processes of manufacturing electric chrome steel wherein theproduct of an openhearth furnace is refined, the steps which consist, intapping such product from the furnace into a suitable receptacle; addingferro-chrome to the'product while the lat- I ter is entering thereceptacle; and establishing an electric current through the steel andferro-chrome as the same enter the receptacle and maintaining same for acomparatively short period.

12. In processes of manufacturing electric low-phosphorus chrome steel,the steps which consist, in creating, in a basic open-hearth furnace,steel of the desired low-phosphorus content; tapping such product fromthe furnace into a suitable receptacle; adding ferro-chrome to theproduct while being tapped; and then subjecting the mixture of steel andchromium to electric treatment.

13. In processes of manufacturing electric low-phosphorus chrome steel,the steps which consist, in creating, in a basic open-hearth furnace,steel of the desired low-phosphorus content; tapping such product fromthe furnace into a suitable receptacle; adding ferro-chrome to theproduct while being tapped; adding lime or a similar product to form asatisfactorily basic slag; and then subjecting the mixture of steel andchromium to electric treatment.

15. In processes of manufacturing electric low-phosphorus chrome steel,thesteps which consist, in creating, in a basic open-hearth furnace,steel of the desired low-phosphorus content; tapping such product fromthe to form a satisfactorily basic slag; and then furnace into asuitable receptacle, allowing subjecting the mixture of steel andchromium some of the slag to remain in the receptacle to electrictreatment. a

to keep the metal hot; adding ferro-chrome Signed by me, this 15" day ofMarch, 10 5 to the product While being tapped; removing 1919.

the slag; adding lime or a similar product JOHN MGCONNELL.

